Cylindrical magnetron having a shunt

ABSTRACT

A magnetron sputtering electrode for use in a rotatable cylindrical magnetron sputtering device, the electrode including a cathode body defining a magnet receiving chamber and a cylindrical target surrounding the cathode body. The target is rotatable about the cathode body A magnet arrangement is received within the magnet receiving chamber, the magnet arrangement including a plurality of magnets. A shunt is secured to the cathode body and proximate to a side of the magnet arrangement, the shunt extending in a plane substantially parallel to the side of the magnet arrangement. A method of fine-tuning a magnetron sputtering electrode in a rotatable cylindrical magnetron sputtering device is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/299,669, filed Jan. 29, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotatable cylindrical magnetronsputtering apparatus having a shunt for fine-tuning the magnetic field.

2. Description of Related Art

A typical magnetron sputtering device includes a vacuum chamber havingan electrode contained therein, wherein the electrode includes a cathodeportion, an anode portion and a target. The term electrode is oftentimesreferred to in the industry as a cathode. In operation, a vacuum isdrawn in the vacuum chamber followed by the introduction of a processgas into the chamber. Electrical power supplied to the electrodeproduces an electronic discharge which ionizes the process gas andproduces charged gaseous ions from the atoms of the process gas. Theions are accelerated and retained within a magnetic field formed overthe target, and are propelled toward the surface of the target which iscomposed of the material sought to be deposited on a substrate. Uponstriking the target, the ions dislodge target atoms from the targetwhich are then deposited upon the substrate. By varying the compositionof the target and/or the process gas, a wide variety of substances canbe deposited on various substrates. The result is the formation of anultra-pure thin film deposition of target material on the substrate.

Over the last decade, the cylindrical magnetron has emerged as theleading technology for sputtering coating on glass substrates. Therotating cylindrical target surface provides for a constant sputteringsurface, thus eliminating the traditional erosion groove and largenon-sputtered areas associated with planar targets. Further, thecylindrical target eliminates large areas of dielectric buildup that canlead to arcing, material flaking, debris, and other processinstabilities. Although the rotatable cylindrical magnetron has itsadvantages over planar magnetrons, the shape of the magnetic field whichdetermines everything from field uniformity and deposition rate totarget utilization may still be optimized further to improve theperformance of the sputtering application. The use of stationaryprofiled magnets can be used to control the shape of the magnetic fieldwhich optimizes the performance of the sputtering application. U.S. Pat.Nos. 5,736,019 and 6,171,461, which are incorporated herein byreference, disclose and attempt to overcome under utilization of targetmaterial via the use of stationary profile magnets. The above-identifiedpatents are directed to magnetron sputtering electrodes that include aplurality of profile magnets, each magnet including a top portion withan apex, wherein each apex is positioned adjacent a target supportingsurface in the cathode body. The magnet cooperates to generate magneticflux lines which form enclosed-looped magnetic tunnels adjacent to thefront sputtering surfaces of the target. As described in theabove-identified patents, these profile magnets result in optimumutilization of target materials at a reasonable rate of utilization. Aproblem with the conventional planar magnet arrangement is that themagnets have flat upper surfaces and, therefore, the target which thematerial is to be sputtered from is not completely utilized.

The development of mid-frequency AC power supplies has enabledcontinuous long-term sputtering of targets which are utilized in areactive gas to form dielectric or poorly conductive thin films. Albeita dramatic improvement above planar targets used in planar cathodes,rotatable cylindrical targets still have a region just beyond themagnetron ends (i.e., turnarounds) which are not sputtered, but rathercollect a portion of the sputtered thin film. When the sputteredmaterial builds up in these turnarounds or unetched regions to asubstantial thickness thus forming an insulating layer, this layer canbecome a source of arcing. Although enabling power supply technology hasincreased process stability of the deposition process, it hassimultaneously introduced increased complexity and cost into the designand arrangement of the hardware associated with the cathode driveassembly which delivers this power to the target surface. The two mostcommon problems associated with the delivery of high power,mid-frequency (20 kHz-120 kHz) current to the cathode are (1) theability of the brush assemblies to carry sufficient current withoutoverheating and eroding due to the “skin-effect” of these frequenciesand (2) the inherent eddy current effects induced by these frequencieswhich can cause extreme localized heating of various components,particularly the support bearing. To circumvent the high currentrequirements, many manufacturers are using custom brush assemblies withhigh silver content in order to overcome the above-mentioned problems.The design and manufacture of custom brushes used in these assembliesare not only costly, but the material is very brittle which can lead toa short operating life. For example, one such solution for addressingthe eddy current problem is to use a custom designed ceramic bearing,which is costly and difficult to replace quickly.

Therefore, it is an object of the present invention to improve theperformance of the cylindrical magnetron sputtering application by usingprofiled magnet arrangements to increase the target utilization and thedeposition rate while reducing the amount of target material on thechamber walls and shielding of a cylindrical magnetron electrode. It isa further object of the present invention to provide an improved driveassembly for a cylindrical magnetron electrode that is designed toreduce the cost and complexity of delivering high power AC current intoa rotating shaft by using common and readily available components.

Further, it is known in cylindrical magnetron sputtering that the filmthickness on the substrate can vary, even when the magnets and targetare perfectly aligned. These coating thickness variations may beattributed to many influences on the sputtering process not associatedwith the magnets. Such influences may include vacuum systemirregularities such as non-uniform anode distribution and non-uniformsystem pumping or gas flow across the length of the target. Whenirregularities in the thickness of the coating on the substrate occur,one can take steps to promote coating uniformity, such as altering thesystem pumping or gas flow, or raising and lowering the relative heightsof the magnets. Such methods of fine tuning the sputtering have somelimitations, however. For example, raising and lowering the magnets onlyallows for tuning on the scale of the fixed lengths of the magnets, andmay not permit for finer tuning on a smaller scale. Accordingly, it isanother object of the present invention to improve the means by whichthe magnetic field may be fine tuned to promote more uniform coating ofthe substrate.

SUMMARY OF THE INVENTION

The present invention provides for a magnet arrangement which is usableas a retrofit magnetic arrangement in a rotatable cylindrical magnetronsputtering electrode. The electrode includes a cathode body defining amagnet receiving chamber, a rotatable cylindrical target surrounding thecathode body, wherein the target is rotatable about the cathode body.The cathode body further defines a magnet arrangement received withinthe magnet receiving chamber, wherein the magnet arrangement includes aplurality of magnets and, wherein at least one of the magnets is aprofiled magnet having a contoured top portion.

The present invention also provides for a rotatable cylindricalmagnetron sputtering device that includes the electrode of the presentinvention and a drive assembly in communication with the cathode bodyand the cylindrical target, wherein the drive assembly comprises a driveshaft and a motor and, wherein the drive shaft is rotatably connected tothe cylindrical target. The drive assembly is adapted to rotate thecylindrical target and to introduce high current AC power into thetarget surface via the rotating drive shaft without adding highlyincremental costs to the overall design of the electrode.

The present invention also includes a magnetron sputtering electrode foruse in a rotatable cylindrical magnetron sputtering device, theelectrode including a target retaining member for holding a rotatablecylindrical target having a first end and a second end with respect tothe axis of the cylindrical target and a cathode body positioned to bewithin the cylindrical target and defining a magnet receiving chamber. Amagnet arrangement is received within the magnet receiving chamber, themagnet arrangement having a first turnaround corresponding to the firstend of the rotatable cylindrical target and a second turnaroundcorresponding to the second end of the rotatable cylindrical target andincluding a plurality of magnets positioned between the first turnaroundand the second turnaround. Each magnet extends from a base of the magnetto a top portion of the magnet in a height direction towards an interiorsurface of the cylindrical target. Considering the magnet arrangement ashaving a length direction, a height direction, and a width direction,the length direction of the magnet arrangement corresponds to the axialdirection of the rotatable cylindrical target, and the height directionof the magnet arrangement corresponds to the height direction of theplurality of magnets. A plurality of shunts is positioned outside of themagnet receiving chamber. The shunts are positioned away from a side ofthe magnet arrangement in the width direction of the magnet arrangement.The shunts are located between the first turnaround and the secondturnaround and arranged at a plurality of different locations withrespect to the length direction of the magnet arrangement. Shunts atdifferent length locations are individually movable relative to themagnet arrangement in at least the height direction, thereby allowingfor tuning of the effect of the magnet arrangement on coating thicknessuniformity along the axial direction of the cylindrical target byadjusting the position of the shunts. The magnetron sputtering electrodemay also include a shunt mount attached to a base plate of the cathodebody, a shunt being secured to the shunt mount. The shunt may alsoinclude an elongated slot, the shunt being secured to the shunt mount bya fastener inserted through the elongated slot and into the shunt mount,such that the shunt may be attached to the shunt mount at a plurality ofheight positions. The position of the shunt may be movable in thedirection of the length of the magnet arrangement. The cathode body mayinclude a central member, wherein the shunt is secured to the centralmember with a clamp, the clamp being movable along the length of thecentral member, such that the shunts may be secured to the centralmember at a plurality of length positions. The shunt may also include anelongated slot and be secured to the clamp by a fastener insertedthrough the elongated slot and into the clamp, such that the shunt maybe attached to the clamp at a plurality of height positions.

The present invention also includes a method of fine-tuning a magnetronsputtering electrode in a rotatable cylindrical magnetron sputteringdevice, utilizing a magnetron sputtering electrode that includes acathode body defining a magnet receiving chamber and a cylindricaltarget surrounding the cathode body, wherein the target is rotatableabout the cathode body. The magnetron sputtering electrode also includesa magnet arrangement received within the magnet receiving chamber, themagnet arrangement including a plurality of magnets. The methodcomprises the steps of identifying a localized region of a substratecoating having a thickness that is non-uniform beyond a predeterminedacceptable deviation; selecting a shunt having a size and shapecorresponding to the localized region; and attaching the shunt to thecathode body, proximate to a side of the magnet arrangement andextending in a plane substantially parallel to the side of the magnetarrangement, at a length position along the length of the magnetarrangement corresponding to the localized region of the substratecoating, and at a height position relative to the height of the magnetarrangement, such that the shunt reduces the magnetic field of themagnet arrangement by an effective amount to cause the thickness of thecoating of the substrate at the localized region to be within thepredetermined acceptable deviation. The magnetron sputtering electrodemay include a central member, wherein the shunt is attached to thecentral member at the length position with a clamp. The shunt mayinclude an elongated slot, wherein the shunt is attached at the heightposition by inserting a fastener through the elongated slot and into theclamp. The magnetron sputtering electrode may further include a shuntmount attached to a base plate of the cathode body, and the shunt mayinclude an elongated slot, wherein the shunt is attached at the heightposition by inserting a fastener through the elongated slot and into theshunt mount.

These and other features and characteristics of the present invention,as well as the methods of operation and functions of the relatedelements of structures and the combination of parts and economies ofmanufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the invention. As usedin the specification and the claims, the singular form of “a”, “an”, and“the” include plural referents unless the context clearly dictatesotherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a rotatable cylindrical magnetronsputtering device made in accordance with the present invention;

FIG. 1A is a top plan view of the magnetron sputtering device shown inFIG. 1;

FIG. 2 is a sectional front view of an electrode of the magnetronsputtering device shown in FIG. 1, wherein magnetic flux lines are shownin relation to a substrate;

FIG. 3 is a sectional view of a cathode body of the electrode shown inFIG. 2;

FIG. 4 is a top plan view, partially in section, of a profiled magnetarrangement of the electrode shown in FIG. 2;

FIG. 5 is a perspective view of a high current brush assembly of therotatable cylindrical magnetron sputtering device shown in FIG. 1;

FIG. 6 is a perspective view of a housing of the high current brushassembly shown in FIG. 5;

FIG. 7 is a sectional view of a cathode vacuum seal chamber of therotatable cylindrical magnetron sputtering device shown in FIG. 1;

FIG. 8 is a cross-sectional view of an electrode of a magnetronsputtering device similar to that shown in FIG. 2, but having twoshunts;

FIG. 9 is a partial cross-sectional view of an electrode of a magnetronsputtering device similar to that shown in FIG. 1, but having twoshunts;

FIG. 10A is a perspective view of a clamp apparatus for mounting theshunts in accordance with the present invention;

FIG. 10B is an end view of the clamp apparatus shown in FIG. 10A;

FIG. 11 is a computer modeled graph showing the magnetic field producedby an un-shunted magnet arrangement;

FIG. 12 is a computer modeled graph showing the magnetic field producedby the magnet arrangement shown in FIG. 11, wherein a shunt is used tocover approximately half the height of one side of the magnetarrangement; and

FIG. 13 is a computer modeled graph showing the magnetic field producedby the magnet arrangement shown in FIG. 11, wherein a shunt is used tocover approximately the entire height of one side of the magnetarrangement.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, the terms “end”, “upper”,“lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”,“lateral”, “longitudinal” and derivatives thereof shall relate to theinvention as it is oriented in the drawing figures. However, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary. Itis also to be understood that the specific devices and processesillustrated in the attached drawings, and described in the followingspecification, are simply exemplary embodiments of the invention. Hence,specific dimensions and other physical characteristics related to theembodiments disclosed herein are not to be considered as limiting.Further, it is to be understood that the invention may assume variousalternative variations and step sequences, except where expresslyspecified to the contrary.

The present invention provides for a rotatable cylindrical magnetronsputtering device 8 that includes an electrode 10 and a drive assembly11 attached to the electrode 10 as shown in FIGS. 1 and 1A. Referring toFIGS. 1 and 2, the electrode 10 includes a hollow cylindrical target 12having an inner surface 13A and an outer surface 13B, a cathode body 14having a first surface 16 and a second surface 18 received within thecylindrical target 12, a base plate 20 attached to the second surface 18of the cathode body 14 and a central member 21 such as a shaft or sleevereceived within the cylindrical target 12 and attached to the base plate20 for supporting the cathode body 14, wherein the cylindrical target 12is rotatable about the cathode body 14 as shown as arrow Z in FIG. 2about the longitudinal axis X. Referring back to FIG. 1, the cylindricaltarget 12 is held in place by an annular target retaining member 23,which is in communication with the drive assembly 11. Attachment of thecathode body 14 to the base plate 20 may be accomplished via one or morefasteners such as screws or bolts B or any other suitable fasteningarrangement known in the art. Attachment of the base plate 20 to thecentral member 21 may be accomplished using a clamp or any othersuitable clamping arrangement known in the art.

Referring to FIGS. 2 and 3, the electrode 10 further includes a guidemember such as a pair of rollers R or other guide assemblies positionedadjacent the cathode body 14 and contacting the inner surface 13A of thecylindrical target 12, thereby allowing the target 12 to rotate aboutthe cathode body 14 at a fixed distance. The cylindrical target 12 maybe, for example, standard titanium hollow tubing having a 5″ insidediameter and a 6″ outside diameter, which is held at a fixed distance,such as 0.60″, away from the first surface 16 of the cathode body 14 toaccount for uniformity adjustments. Referring to FIG. 2, a substrate Sis positioned directly above the cathode body 14, wherein targetmaterial is sought to be deposited onto the substrate S. Chamber walls22 surrounding the electrode 10 and the substrate S provide a shieldingfor the sputtering application.

Referring to FIGS. 2-4, the cathode body 14 forms a magnet receivingchamber, which contains a profiled magnet arrangement 24. The profiledmagnet arrangement 24 uses profiled magnets as shown and described inU.S. Pat. Nos. 5,736,019 and 6,171,461 which are hereby incorporated byreference in their entirety. The magnet arrangement 24 includes aprofiled central magnet 26 and profiled end magnets 28A, 28B. Each ofthe profiled magnets 26, 28A and 28B has a base 30 and a contoured topportion 32. The shape of the contoured top portion 32 is shown angled,but may include sloped, conical, parabolic, convex, and concave shapes.If the contoured top portion 32 is angled, it is preferable for an apexof the contoured top portion 32 to be flat, desirably between 0.01 inchto 0.060 inch or up to half the thickness of the magnets 26, 28A and28B. Having a flat apex minimizes the possibility of chipping themagnets 26, 28A and 28B during routine use of the completed assembly.Alternatively, the apex may come to a point. The use of such contouredshapes is conducive to directing magnetic flux lines from the contouredtop portion 32 of each of the magnets 26, 28A and 28B.

With continued reference to FIGS. 2 and 3, the top portion 32 of theprofiled end magnets 28A, 28B is preferably angled on one side away fromthe central magnet 26 wherein the apex of the top portion 32 is adjacentto the central magnet 26. The top portion 32 of the central magnet 26 ispreferably angled on both sides, wherein the apex of the top portion 32is at the center of the central magnet 26. The magnet arrangement 24 isalso shown using a planar magnet having flat surfaces as shown inphantom in FIGS. 2 and 3. The primary magnetic field lines L generatedfrom the profiled magnets 26, 28A and 28B are more centered than themagnetic field lines L′ (shown in phantom) generated from planarmagnets, such that an overall width W of field lines L is less than anoverall width W′ of the field lines L′ as shown in FIG. 2. The fieldlines L using the profiled magnets 26, 28A and 28B reduce the off anglesputtering that is inherent to the sputtering process, thus resulting inmore of the target sputtering material on the substrate S and less onthe chamber walls 22. For example, a computer simulation demonstratedthat the magnetic flux lines F generated using the profiled magnetarrangement 24 resulted in an angle reduction of about 15 degreescompared to the magnetic flux lines F′ (shown in phantom in FIG. 2)generated using the planar magnet arrangement (i.e., an angle Aapproximately 15 degrees and angle A′ approximately 30 degrees), thusreducing the amount of sputtered material on the chamber walls 22 fromabout 16.7% to 9.2%. When the sputtered material builds up on thechamber walls 22, it can fall off onto the target 12 or the substrate Sthus causing the device to short out or create debris which would reducethe yield or quality of substrate S.

Further, the use of the profile magnets 26, 28A and 28B in electrode 10provides for a greater increase in magnetic field intensity using thesame size magnets in contrast to conventional planar magnets. Thisincrease in the magnetic field intensity and the reduction of fluxmaterial on the chamber walls 22 result in an overall rate increase andtarget utilization in the electrode 10 of the present invention.

Initial processing uniformity may be established by adjusting thedynamic field stroke along the length of the electrode 10 to compensatefor known facts such as the tendency for the magnetron ends (i.e.turnaround) to sputter at faster rates than at the center of the target12. Therefore, it is contemplated that the ends of the central magnet 26of the profiled magnet arrangement 24 have a diverter magnet D of adifferent profile such as is shown in FIG. 4. This magnet having adifferent profile can slow down the sputtering effect at the ends, thusreducing erosion of the target 12 at these ends.

Referring to FIG. 1, the drive assembly 11 of the magnetron sputteringdevice 8 includes a drive unit 34, wherein the drive unit 34 includes adrive shaft 36 and a motor 38. The drive shaft 36 is rotatably coupledto the retaining member 23. The motor 38 is coupled to the drive shaft36, so that activation of the motor 38 causes the drive shaft 36 torotate about an axis “X”, which in turn causes the retaining member 23having the attached cylindrical target 12 to rotate about the cathodebody 14. The drive assembly 11 further includes a brush assembly 40surrounding the drive shaft 36, wherein the brush assembly 40 coactswith the rotating drive shaft 36 to supply AC and DC electrical currentto the cathode body 14, and a cathode vacuum seals and supports chamberassembly 60 for introducing high current AC power from the atmosphereinto the rotating vacuum drive shaft 36 with negligible eddy currentheating effects. The remaining components of the drive assembly 11 willnot be described because these components are known in the art and arecommon for typical rotating cylindrical magnetron sputtering devices.

Referring to FIG. 1, the drive shaft 36 is electrically connected to thecentral member 21, which is affixed to the base plate 20 of the cathodebody 14. Rotation of the drive shaft 36 causes the brush assembly 40 togenerate high electrical current to the drive shaft 36, which transfersthe current through the central member 21 and to the base plate 20 andthen to the cathode body 14. The central member 21 may be, for example,a shaft made of a conductive material in order to carry electricalcurrent to the cathode body 14.

FIGS. 5 and 6 show the high current brush assembly 40 that includes adisc-shaped housing 42 defining a central opening 44 therein, aplurality of circumferentially spaced spacers 46 arranged on a frontsurface 48 of the housing 42, a plurality of brushes 50 positionedbetween each spacer 46 and a cap 52 attached to the front surface 48 ofthe housing 42. The housing 42 is preferably made of copper. The brushes50 may be standard motor brushes made of, for example, a metal graphitematerial such as a low grade graphite or a graphite having a slightlyhigher conductivity. These brushes are readily available by most majorsuppliers of motors. In operation, specifically when operating at highcurrents in the AC power mode, cooling of the brushes 50 is required toincrease further the current capacity of the brushes 50. FIG. 6 showsthe housing 42 without the cap 52 being supplied with cooling water asrepresented by arrows A, which circulates within the housing 42 therebycooling the brushes 50. Compression of the brushes 50 onto the rotatingshaft 36 extending through the opening 44 is achieved by the use of agarter spring 54 shown in FIG. 5. By using small individual segments ofbrushes 50 and a copper housing 42, the surface area of the entire brushassembly 40 is increased as well as the ability to cool the brushes 50,thereby achieving a higher current capacity.

FIG. 7 shows a sectional view of the cathode vacuum seals and supportchamber assembly 60 that includes a housing 62 and a wear sleeve 64centrally positioned within the housing 62. An insulating member 66 ispositioned between a wall W of the housing 62 and the sleeve 64 forelectrically insulating the housing 62 from high voltage and electricalcurrent. Atmosphere to vacuum seals are achieved through static O-rings68 positioned between the housing wall W and the insulating member 66 aswell as spaced rotary vacuum seals 70 positioned between the sleeve 64and the insulating member 66. Spacer blocks 72 and 74 keep the rotaryseals 70 spaced apart and aligned. The drive shaft 36 carrying thecurrent (shown in FIG. 1) extends through the sleeve 64 and rotatesabout axis “X”, wherein the sleeve 64 functions as a front supportbushing as well as a vacuum seal surface. A graphite or plastic bearing76 is located between the sleeve 64 and the vacuum seals 70. Preferably,the bearing 76 may be manufactured from highly durable plastics such aspolyimides or from highly durable graphite. The size of the bearing 76may vary depending on the cathode size and the spacers 72, 74 as well asthe sleeve 64. It is important to preferably use materials for thecomponents that cannot only support a load induced by the cathode, butalso prevent eddy currents from setting up, thereby causing extremeheating. For example, conductive materials such as highly durableplastics may be used for the bearing 76 and the other components withinthe vacuum assembly 60 because the high voltage is kept off of thevacuum housing 62 by the insulating member 66, thereby making thesecomponents non-susceptible to eddy current heating.

The present invention also provides for a method of improving targetutilization and deposition rate in a cylindrical magnetron sputteringapplication that includes providing a substrate S and a rotatablecylindrical magnetron device 8 of the present invention. The cylindricaltarget 12 is rotated around a magnet arrangement 24 and target materialfor the cylindrical target 12 is obtained and deposited on the substrateS.

In the event that the thickness of a substrate coating in a localizedregion is non-uniform beyond a predetermined acceptable deviation, suchas within 2-5% uniformity, fine tuning of the magnetic field from themagnet arrangement 24 may be desired.

FIGS. 8 and 9 show an embodiment of a cylindrical sputtering magnetronhaving a shunting mechanism which may be used to fine tune the magneticfield to promote uniform coating of the substrate. FIG. 8 is across-sectional view similar to FIG. 2, and FIG. 9 is a cross-sectionalview of the electrode portion of the sputtering magnetron device similarto the view in FIG. 1. The electrode 10 and magnet arrangement 24 shownin FIGS. 8 and 9 are intended to be exemplary. As will be understood bythose skilled in the art, the present shunting invention may be utilizedwith various alternative cylindrical sputtering apparatuses havingdifferent electrode and magnet arrangement 24 configurations. Asillustrated in FIG. 8, the magnetron sputtering electrode 10 includes acathode body 14 defining a magnet receiving chamber, a cylindricaltarget 12 surrounding the cathode body 14, a magnet arrangement 24received within the magnet receiving chamber, and a plurality of shunts104 secured to the cathode body 14 outside of the magnet receivingchamber. Considering the magnet arrangement as having a lengthdirection, a height direction, and a width direction, with the lengthdirection of the magnet arrangement corresponding to the axial directionof the rotatable cylindrical target, and the height direction of themagnet arrangement corresponding to the height direction of a pluralityof magnets of the magnet arrangement, the plurality of shunts arepositioned away from a side of the magnet arrangement in the widthdirection of the magnet arrangement. Each magnet extends from a baseportion in the height direction of the magnet arrangement towards aninterior surface of the cylindrical target.

Referring to FIG. 8, attached to the base plate 20 are two shunt mounts100. The shunt mounts 100 extend in a plane substantially perpendicularto the base plate 20 and substantially parallel to the magnetarrangement 24. The shunt mounts shown in FIG. 2 are attached to thebase plate 20 via screws 102, but may be attached via other fasteningmeans known in the art such as nuts and bolts, clamps, or welds. Theshunt mounts 100 may also be attached to the central member 21 or otherportion of the electrode, as long as the shunt mounts are securelymounted and are stationary with respect to the magnet arrangement 24.FIGS. 10A and 10B show a shunt assembly wherein shunts 104 may beattached to the magnet support tube or central member 21 with clamps 110around the magnet support tube or central member 21. The clamps 110 canbe movably positioned along the length of the magnet support tube tochange the location of the shunts 104 to any of a plurality of distinctpositions, so as to place the shunts 104 at a length positioncorresponding to the localized region of the non-uniform substratecoating.

Referring again to FIGS. 8 and 9, attached to the outer surfaces of theshunt mounts 100 are two shunts 104. The shunts 104 are essentiallyrectangular plates made from a ferromagnetic material such as stainlesssteel or any other suitable magnetic material. The shunts 104 are placedin a position away from a side of the magnet arrangement 24 with respectto the width direction of the magnet arrangement to influence themagnetic field by generally shunting the field, or inhibiting themagnetic flux from the magnet arrangement 24 through the shunts 104.Like the shunt mounts 100, the shunts 104 extend in a planesubstantially perpendicular to the base plate 20 and substantiallyparallel to the magnet arrangement 24. The shunts 104 are secured to theshunt mounts 100 via fasteners or screws 106 inserted through elongatedslots 108 in the shunts 104. The slots 108 are wide enough such that thethreaded portion of the screw 106 may fit through the slot 108 and intothe shunt mount 100, but narrow enough that the head of the screw 106does not fit through the slot 108, in order that the shunts 104 may besecurely attached to the shunt mounts 100. Similarly, as shown in FIGS.10A and 10B, fasteners or screws 106 and slots 108 may be used to attachthe shunts 104 to the clamps 110.

The shapes, lengths, heights, and widths of the shunt mounts 100 andshunts 104 may vary depending upon the positioning and amount ofshunting desired by a user of the magnetron sputtering apparatus. Theshunts 104 shown in FIG. 9 are located between a first turnaround of themagnet arrangement and a second turnaround of the magnet arrangement, atwhich diverter magnets may be positioned as previously discussed, andthe shunts shown in FIG. 9 have different sizes, with the shunt 104 onthe left being generally smaller than the one on the right. Further, thescrews 106 and elongated slots 108 permit the shunts 104 to be movablypositioned with respect to the magnet arrangement 24. In particular, thescrews 106 may be loosened freeing the shunts 104 to move upward ordownward along the direction of the slots 108, and then the screws 106may be tightened again to re-secure the shunts 104 to the shunt mounts100. The shunts 104 may thus be positioned in a plurality of distinctheight positions. For example, the left shunt 104 in FIG. 9 ispositioned to cover approximately half the height of the magnetarrangement 24, whereas the right shunt 104 in FIG. 9 is positioned tocover approximately the entire height of the magnet arrangement 24. Asis further explained below and shown in FIGS. 11-13 at differentlocations, are individually movable relative to the magnet arrangementin at least the height direction. The height position of the shunts 104directly affects the magnetic flux density at the surface of the target,with more coverage by the shunts 104 generally resulting in a lowermagnetic flux density at the target. One or more shunts 104 may beplaced on one or both sides of the magnet arrangement 24, as is requiredto produce the desired shunting effect. As will be appreciated by thoseskilled in the art, the dimensions of the shunts 104 and the slots 108may be varied in order to allow other amounts of coverage and shuntingof the magnet arrangement 24.

The ability to vary the size, shape, and position of the shunts 104 inaccordance with the present invention allows for precise fine tuning ofthe sputtering to ensure uniform coating of the substrate. For example,if a localized portion of a coating on a substrate were non-uniformlythick beyond an acceptable deviation, one way to adjust the resultingthickness would be to reposition the magnet heights in the magnetarrangement 24 near the area which is too thick. However, a typicalmagnet length in such an arrangement is fixed and might be about 20inches typically, and so such repositioning of magnet heights would be arelatively crude tuning of the sputtering apparatus. By contrast, usingthe present invention, one can place a shunt 104 having an essentiallyinfinite variety of shapes, sizes, and positions to shunt the magneticfield of the magnet arrangement 24. In this way, if a coating thicknessirregularity is smaller than the size of the magnets, a smaller andprecisely sized and placed shunt can be utilized to influence themagnetic field in a way that will reduce the coating thickness in thelocalized region of excessive thickness. Thus, a shunt 104 may beselected for its shape and size to correspond to the non-uniformlocalized region of the substrate coating in a manner more precise thanthe scale of the magnets in the magnet arrangement 24. Generally, theshunts 104 should be selected and positioned with an appropriate heightposition and length position to produce an effective amount of shunting,i.e., an amount that results in uniform coating of the substrate withinthe predetermined acceptable deviation.

FIGS. 11-13 are three computer modeled graphs showing the variousmagnetic fields produced by a magnet arrangement 24 that is unshunted,one that includes a shunt 104 covering half the height of one side ofthe magnet arrangement 24, and one that includes a shunt 104 coveringthe entire height of one side of the magnet arrangement 24,respectively. Generally the shunting on one side of the magnetarrangement 24 reduces the maximum magnetic field strength at thetarget, and causes the field to become asymmetrical with respect to themagnet arrangement 24. More coverage of the magnet arrangement 24 by theshunt 104 causes a greater decrease in the field strength, and a greaterdegree of field asymmetry. In particular, for the examples of FIGS.11-13, the un-shunted magnet arrangement in FIG. 11 yields a magneticflux density of approximately 570 G at the target surface. With theshunt 104 positioned to cover approximately half of one side of themagnet arrangement 24 in FIG. 12, the magnetic flux density is reducedto approximately 400 G at the target surface. Positioning the shunt 104to cover approximately the entire side of the magnet arrangement 24 inFIG. 13 lowers the magnetic flux density to approximately 360 G.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. The presentlypreferred embodiments described herein are meant to be illustrative onlyand not limiting as to the scope of the invention which is to be giventhe full breadth of the intended claims and any and all equivalentsthereof.

The invention claimed is:
 1. A magnetron sputtering electrode for use ina rotatable cylindrical magnetron sputtering device, the electrodecomprising: a target retaining member for holding a rotatablecylindrical target, the rotatable cylindrical target having a first endand a second end with respect to the axis of the cylindrical target; acathode body positioned to be within the cylindrical target and defininga magnet receiving chamber; a magnet arrangement received within themagnet receiving chamber, the magnet arrangement having a firstturnaround corresponding to the first end of the rotatable cylindricaltarget and a second turnaround corresponding to the second end of therotatable cylindrical target, the magnet arrangement comprised of aplurality of magnets positioned between the first turnaround and thesecond turnaround, wherein each magnet extends from a base of the magnetto a top portion of the magnet in a height direction towards an interiorsurface of the cylindrical target, wherein the magnet arrangement has alength direction, a height direction, and a width direction, wherein thelength direction of the magnet arrangement corresponds to the axialdirection of the rotatable cylindrical target, and wherein the heightdirection of the magnet arrangement corresponds to the height directionof the plurality of magnets; and a plurality of shunts outside of themagnet receiving chamber and spaced away from a side of the magnetarrangement in the width direction of the magnet arrangement, andwherein the plurality of shunts is located between the first turnaroundand the second turnaround and arranged at a plurality of differentlocations with respect to the length direction of the magnetarrangement, and wherein the shunts at different length locations areindividually movable relative to the magnet arrangement in at least theheight direction, thereby allowing for tuning of the effect of themagnet arrangement on coating thickness uniformity along the axialdirection of the cylindrical target by adjusting the position of theshunts.
 2. The magnetron sputtering electrode of claim 1, furthercomprising a shunt mount attached to a base plate of the cathode body,at least one shunt being secured to the shunt mount.
 3. The magnetronsputtering electrode of claim 2, wherein the at least one secured shuntincludes an elongated slot and is secured to the shunt mount by afastener inserted through the elongated slot and into the shunt mount,such that the at least one secured shunt is capable of being attached tothe shunt mount at a plurality of height positions.
 4. The magnetronsputtering electrode of claim 1, wherein the position of the shunts atdifferent length locations are individually movable in the lengthdirection of the magnet arrangement.
 5. The magnetron sputteringelectrode of claim 4, the cathode body further comprising a centralmember, wherein at least one shunt is secured to the central member witha clamp, the clamp being movable along the length of the central member,such that the at least one secured shunt is capable of being secured tothe central member at a plurality of length positions.
 6. The magnetronsputtering electrode of claim 5, wherein the at least one secured shuntincludes an elongated slot and is secured to the clamp by a fastenerinserted through the elongated slot and into the clamp, such that the atleast one secured shunt is capable of being attached to the clamp at aplurality of height positions.
 7. The magnetron sputtering electrode ofclaim 1, wherein a distance between a closest portion of at least oneshunt and a center of the magnet arrangement is greater than a distancebetween a farthest portion of the magnet arrangement and the center ofthe magnet arrangement.
 8. The magnetron sputtering electrode of claim2, wherein the at least one secured shunt is secured to an outer surfaceof the shunt mount, such that the shunt mount is disposed between the atleast one secured shunt and the magnet arrangement.
 9. The magnetronsputtering electrode of claim 2, wherein the at least one secured shuntis formed from a ferromagnetic material, and wherein the ferromagneticmaterial is secured to the shunt mount.
 10. The magnetron sputteringelectrode of claim 9, wherein the at least one secured shunt includes anelongated slot in the ferromagnetic material, wherein the at least onesecured shunt is secured to the shunt mount by a fastener insertedthrough the elongated slot and into the shunt mount, such that the atleast one secured shunt is capable of being attached to the shunt mountat a plurality of height positions.
 11. A magnetron sputtering electrodefor use in a rotatable cylindrical magnetron sputtering device, theelectrode comprising: a target retaining member for holding a rotatablecylindrical target, the rotatable cylindrical target having a first endand a second end with respect to the axis of the cylindrical target; amagnet arrangement positioned to be within the cylindrical target, themagnet arrangement having a first turnaround corresponding to the firstend of the rotatable cylindrical target and a second turnaroundcorresponding to the second end of the rotatable cylindrical target, themagnet arrangement comprised of a plurality of magnets positionedbetween the first turnaround and the second turnaround, wherein eachmagnet extends from a base of the magnet to a top portion of the magnetin a height direction towards an interior surface of the rotatablecylindrical target, wherein the magnet arrangement has a lengthdirection, a height direction, and a width direction, wherein the lengthdirection of the magnet arrangement corresponds to the axial directionof the rotatable cylindrical target, and wherein the height direction ofthe magnet arrangement corresponds to the height direction of theplurality of magnets; a plurality of shunts spaced away from a side ofthe magnet arrangement in the width direction of the magnet arrangement,wherein the shunts are located between the first turnaround and thesecond turnaround and arranged at a plurality of different locationswith respect to the length direction of the magnet arrangement, andwherein the shunts at different length locations are individuallymovable relative to the magnet arrangement in at least the heightdirection, thereby allowing for tuning of the effect of the magnetarrangement on coating thickness uniformity along the axial direction ofthe cylindrical target by adjusting the position of the shunts.
 12. Themagnetron sputtering electrode of claim 11, further comprising: a hollowcentral member positioned to be within the cylindrical target anddefining an axis of the cylindrical target; and a base plate fixed tothe central member and extending along an axial direction of thecylindrical target, the base plate having a lower surface facing thecentral member and an upper surface for facing the cylindrical target,wherein the magnet arrangement is positioned on the upper surface of thebase plate, each magnet including a base portion facing the uppersurface of the base plate and a top portion for facing the cylindricaltarget.
 13. The magnetron sputtering electrode of claim 11, wherein theplurality of shunts includes a plurality of first shunts spaced awayfrom a side of the magnet arrangement in a first direction and aplurality of second shunts spaced away from a side of the magnetarrangement in a second direction opposite to the first direction. 14.The magnetron sputtering electrode of claim 13, wherein the shunts areindividually movable in a direction towards and away from the baseplate.
 15. The magnetron sputtering electrode of claim 13, wherein theshunts are individually movable in an axial direction of the cylindricaltarget.
 16. The magnetron sputtering electrode of claim 13, wherein theshunts include a plurality of sizes of shunts.